iOS 9.3.5 was a nightmare for reverse engineers for two primary reasons. First, it patched the Trident vulnerabilities: a WebKit vulnerability to achieve remote code execution, a memory corruption issue in the kernel to break the sandbox, and an information leak to bypass KASLR (Kernel Address Space Layout Randomization). Second, it incorporated all prior mitigations, including KPP, which actively checks for unauthorized modifications to the kernel core.
: iOS 9.3.5 was the final firmware for many 32-bit devices. If you are on a 64-bit device (like an iPhone 5s or newer), these specific tools will not work. App Compatibility ios 9.3.5 untethered jailbreak